Percutaneous transluminal angioplasty in a canine model of cerebral vasospasm: angiographic, histologic, and pharmacologic evaluation

Cerebral artery restenosis following transluminal balloon angioplasty for vasospasm after subarachnoid hemorrhage

Background:

Although percutaneous transluminal angioplasty (PTA) is a widely used less invasive method to treat coronary artery stenosis, 10% of treated patients experience restenosis. Restenosis also occurs in approximately 5% of patients subjected to carotid artery stenting. Animal and human data suggested that restenosis is a response to injury incurred during PTA. As PTA has come into wide use to manage symptomatic cerebral vasospasm after subarachnoid hemorrhage (SAH) we studied the incidence of restenosis after PTA for cerebral vasospasm.

Methods:

Our study population consisted of 32 patients who had undergone PTA. They were followed by cerebral or 3DCT angiography or MRA for 6 126 months post-PTA (mean 48.65 months) to diagnose restenosis of the cerebral artery. We compared the size of the cerebral artery on the PTA and the contralateral side.

Results:

All 32 patients underwent successful PTA of 38 vascular territories and all manifested angiographic improvement of vasospasm. None suffered restenosis during the follow up period.

Conclusion:

PTA resulted in a significant improvement in the vessel diameter in patients with vasospasm after SAH and they did not suffer restenosis in the course of prolonged follow-up.

Long-term effects of in vivo angioplasty in normal and vasospastic canine carotid arteries: pharmacological and morphological analyses

OBJECT

A canine model of hemorrhagic vasospasm of the high cervical internal carotid artery (ICA) was used to study the long-term effects of transluminal balloon angioplasty (TBA) on the structure and function of the arterial wall.

METHODS

Forty dogs underwent surgical exposure of both distal cervical ICAs, followed by baseline angiographic studies on Day 0. Dogs in Group A (20 animals) underwent simple exposure of one ICA and placement of a silicone elastomer cuff around a segment of the opposite artery. These animals underwent repeated angiography on Day 7, and then TBA was performed on the uncuffed ICA; the cuff was removed from the opposite vessel. For dogs in Group B (20 animals), blood clot-filled cuffs were placed around both ICAs, and on Day 7 angiography was repeated and TBA was performed on one randomly selected ICA. Four animals were then killed from each group, and in the remaining animals the cuffs were removed from both ICAs. On Days 14, 21, 28, and 56, four animals from each group underwent repeated angiography and were then killed to permit pharmacological and morphological analyses of the ICAs. This protocol yielded five study categories: cuffed nonblood-coated arteries not subjected to TBA, blood-coated arteries not subjected to TBA, blood-coated arteries subjected to TBA, normal arteries subjected to TBA, and control arteries obtained from the proximal ICA in each animal. The contractile responses of isolated arterial rings obtained from each ICA were recorded after treatment with potassium chloride, noradrenaline, and serotonin, whereas relaxations in response to the calcium ionophore A23187 and papaverine were recorded after tonic contraction to noradrenaline had been established. Morphological analysis was performed using scanning electron microscopy. Arteries surrounded by an empty cuff exhibited no angiographic, pharmacological, or morphological differences compared with normal arteries on any study day. Arteries surrounded by blood developed angiographically confirmed vasospasm on Day 7, with characteristic pharmacological and morphological features; resolution of these symptoms occurred by Day 21. Vasospastic arteries subjected to TBA on Day 7 remained dilated on angiographic studies, exhibited impaired responses to pharmacological agents (except for papaverine), and showed altered morphological features until Day 28. Normal arteries subjected to TBA on Day 7 remained dilated on angiographic studies, exhibited impaired responses to pharmacological agents (except for papaverine), and displayed altered morphological features until Day 14.

CONCLUSIONS

These results indicate that the canine high cervical ICA model produces consistent and reproducible vasospasm that follows a similar time course to that seen in humans. When TBA is performed in vasospastic arteries, it results in an immediate functional impairment of vascular smooth muscle that lasts for 2 weeks, with resolution at 3 weeks; morphological changes are mostly resolved 3 weeks post-TBA. In normal vessels, TBA causes functional impairment and morphological alterations that are not as severe or as long-lasting as those seen in vasospastic arteries.

Accentuated Vasospasm during Treatment of an Acutely Ruptured Aneurysm with Electrolytically Detachable Coils: Coincidence or Causation?

We report an unusual case of precipitous worsening of vasospasm associated with subarachnoid haemorrhage that developed during endosaccular coil embolisation of a ruptured posterior communicating aneurysm. The acutely worsening vasospasm occurred in the distal ipsilateral anterior circulation remote from the site of microcatheter manipulation, resulting in transient occlusion. Despite successful endovascular treatment of both the aneurysm and vasospasm, the patient continued to clinically decline and eventually died. This case raises important issues regarding the potential mechanisms and optimal therapeutic strategies for this complication, which are reviewed.

Balloon angioplasty for the treatment of vasospasm: results of first 50 cases

OBJECTIVE

To report the results of the first 50 consecutive patients with vasospasm secondary to subarachnoid hemorrhage treated with balloon angioplasty after failure of medical management.

METHODS

Retrospective uncontrolled study of 50 consecutive patients treated with balloon angioplasty between February 1988 and July 1992. Forty-six had objective clinical deterioration despite maximal medical therapy, whereas four were treated on the basis of rapidly accelerating transcranial Doppler velocities and decreased regional blood perfusion detected by technetium-99m-exametazime brain single photon emission computed tomography. All patients had evidence of marked vasospasm demonstrated by angiography. Thirty-two (64%) and 46 (92%) patients underwent angioplasty within 12 and 18 hours, respectively.

RESULTS

Of the patients with clinical evidence of vasospasm-induced ischemia, 28 (61%) showed sustained neurological improvement within 72 hours of angioplasty. Three (6%) patients deteriorated within 72 hours after angioplasty, with two (4%) patients dying immediately after angioplasty as a result of vessel rupture and the other patient's Glasgow Coma Scale score decreasing by 2. Two additional patients in poor condition with Hunt and Hess Grade V at the time of angioplasty subsequently died during hospitalization. Two other patients died as a result of unclipped aneurysms that subsequently bled 4 and 12 days after angioplasty, respectively. The improvement demonstrated clinically, angiographically, and by transcranial Doppler after angioplasty was sustained, with only one patient requiring subsequent angioplasty of a previously dilated segment (total, 170 vessel segments dilated). Two patients developed vasospasm in previously undilated segments.

CONCLUSION

Timely balloon angioplasty can reverse delayed ischemic deficit caused by vasospasm in patients for whom medical therapy has failed.